A quick trip to IMDB later and I realized that quite a few of the show’s one-hit wonders — the sole stipulation for inclusion in this list — would get major attention if they guest starred on a TV series today. We’re talking Britney Spears on “How I Met Your Mother”-big. So who are these mystery celebrities? All will be revealed after the jump!

Kat Dennings as Jenny Briar in “Hot Child in the City”

The star of “Nick and Norah’s Infinite Playlist” and “The House Bunny” channeled her inner bitch for her role as spoiled Jenny, who hired Samantha to do the PR for her bat mitzvah in the third season’s 15th episode. Oh, and for the record, her friends braces are sapphire. Remember that!

Elizabeth Banks as Catherine in “Politically Erect”

Elizabeth, who was credited as Elizabeth Maresal Mitchell in the ep, easily has the highest ratio of on-screen time to 2009 fame. Her appearance lasts all of 15 seconds — consisting of interrupting her husband’s conversation with Charlotte at golden shower aficionado Bill Kelley’s fundraiser.

Bradley Cooper as Jake in “They Shoot Single People, Don’t They?”

Carrie is feeling bad about herself following a disastrous New York cover shoot — “Single and Fabulous, question mark?” — so she indulges in a few tartinis and a fellow smoker, Jake. But her happiness is short lived once Jack finds a copy of the magazine, thrusting the picture — and the truth — in Carrie’s face.